1. Field of the Invention
The present invention relates to an oil separator structure for use in separating oil contained in blow-by gas exhausted from an internal combustion engine, and more particularly, to both an arrangement and a construction of an oil separator chamber.
2. Description of the Background Art
As one example of the oil separator of the conventional internal combustion engine, there is provided an oil separator disclosed in the gazette of Japanese Examined Utility Model Publication No. Hei 6-27778. As shown in FIG. 9 of the perspective view showing an exploded state, a frame-like outer circumferential wall 06 projected outwardly is integrally arranged in cooperation with a sidewall 05 ranging from a lower part of a vertical wall of a cylinder block 01 to a skirt segment in an oil separator 03 installed at an outside segment of the cylinder block 01. A lid plate 07 is connected to the outer circumferential wall 06. Thereby, an oil separator chamber 04 is formed by the cylinder block side wall 05, the outer circumferential wall 06 and the lid plate 07.
Although a plurality of oil baffles 013, 014 are arranged within this oil separator chamber 04 so as to cause its inner side to become a labyrinth, the outer circumferential wall 06 is arranged to enclose a part of the reinforcing rib 015 of the cylinder block 01. This reinforcing rib 015 is constituted as one oil baffle 013 within the oil separator chamber 04. As shown in FIG. 9, another oil baffle 014 is cooperatively arranged within a predetermined range of the sidewall 05 of the cylinder block 01. Then, both a blow-by gas intake port 011 and a blow-by gas exhaust port 012 are arranged at positions where these oil baffles 013, 014 are held. The blow-by gas intake port 011 is formed at the cylinder block sidewall 05 in a punched-out shape and the blow-by gas exhaust port 012 is formed at the lid plate 07.
In addition, the oil separator disclosed in the gazette of Japanese Patent Laid-Open No. Sho 61-138811 as another example of the oil separator of the conventional internal combustion engine is constructed such that a side surface of the cylinder head 021 is provided with a cap 026 for sealingly closing a cam shaft mounting space 023 of a four-stroke engine of a type in which a cam shaft 022 is pivotally supported at the cylinder head 021 as shown in FIG. 10. The cam shaft 022 is driven by a sprocket 024 and a chain 025 or the like installed between it and a crank shaft (not shown).
The cap 026 is formed by a hollow member and at the same time its inner space 027 is communicated with the crank chamber and the surrounding atmosphere to act as a breather chamber. That is, the cap 026 is formed with both a gas inlet 029 communicating the inner space 027 with a cam shaft mounting space 023, and an oil return hole 030 communicated with a chain tunnel 028. The upper segment of the cap 026 is provided with a surrounding atmosphere communication hole 031 communicating the inner space 027 with the surrounding atmosphere. In addition, ribs 032, 032 alternatively projecting from both its inner wall and outer wall are formed in the inner space 027 to constitute a labyrinth for gas flowing in the inner space 027.
In the aforesaid oil separator of the conventional internal combustion engine, the oil separator was formed by assembling the baffle plates or lid plate, and cap or the like to composing members of the internal combustion engine such as the cylinder block or the cylinder head and the like, so that this prior art had a problem that the number of component elements and the number of assembling steps are increased.
In order to solve the aforesaid problem, the oil separator structure of the internal combustion engine of the present invention is characterized in that an oil separating chamber for separating oil contained in blow-by gas is arranged outside a transmission member passage connecting a crank shaft with a cam shaft of a valve system and at an abutting surface between a cylinder block and a cylinder head. Partition walls are alternatively arranged at the cylinder block and the cylinder head perpendicular to the abutting surface for dividing the oil separating chamber into a plurality of small subchambers to form a labyrinth structure. The small subchamber at one end of the plurality of small subchambers is provided with a blow-by gas intake passage communicated with the transmission member passage. The small subchamber at the other end of the plurality of small subchambers is provided with a blow-by gas exhaust passage for returning blow-by gas to an air cleaner. Each of the small subchambers not provided with the blow-by gas intake passage is provided with an oil return passage communicating with the transmission member passage.
The present invention is constructed as described above and the oil separator structure is formed under utilization of an abutting surface between the cylinder block and the cylinder head of the basic structural members of the internal combustion engine, so that the number of component elements and the number of assembling steps are reduced as compared with the prior art, and so the costs become less expensive.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.